Frequently, conduits, ducts, hoses, pipes and the like conduct explosive fluids from a supply into a chamber. If an explosion occurs, for example in the line, the explosion can travel through the fluid into the chamber; likewise, if an explosion occurs in the chamber, the communicating line can transfer the resulting explosion to the supply chamber. In order to relieve explosive pressures, for example in the receiving chamber, it has previously been proposed to provide the receiving chamber with a protective cap which can open the chamber to the atmosphere. Such protective caps may also be supplied in form of cover plates and the like which are releasable under predetermined stresses, for example stresses due to an explosion.
Explosive fluids which are handled in such apparatus may, for example, be combustion gases, mixtures of air and combustible powder or dust such as sawdust, grains, wheat, coal dust or the like. Flame blocks or chokes are known, but, usually, to protect apparatus against destruction due to explosion, pressure relief valves or pressure relief arrangements are used. As a general principle, an initially closed system is opened upon occurrence of excessive pressure therein; the opening may occur immediately or after some time delay. Thus, the initially closed system is vented, either for a short time or continuously after the occurrence of the explosion. The venting can be directed to a region where no dangerous consequences are expected. Due to the construction of such venting arrangements, build-up of excessive explosion pressure within the overall system is prevented and thus bursting of components of the system due to the explosion likewise is prevented.
A flame front within ducts, pipes or the like can be inhibited from progressing along the duct by directing the line coming from the explosion site directly to the protective opening cap or region; lines or ducts which are to continue to supply materials from the chamber then are coupled to the chamber from the opposite end thereof. Thus, an explosion which is transmitted through the line or duct is vented quickly into space, directed, usually, upwardly. Any explosive force which may propagate towards the downwardly directed further connecting line would occur with substantially lesser speed and under reduced pressure, and hence dangerous conditions.